Geographical variation in disease progression in HIV-1 seroconverted injecting drug users in Europe?

Background Human immunodeficiency virus (HIV) disease progression might var y by geographical region due to differences in the spectrum of HIV-related illnesses and (access to) health care. Therefore, the effect of geographica l region, next to the effect of other potential cofactors, on disease progr ession in 664 injecting drug users (IDU) with documented HIV seroconversion from eight cohorts in Europe was studied. Methods Kaplan-Meier methods and Cox proportional hazards analysis were per formed to assess the effect of geographical region, other sociodemographics , drug use and repeated HIV exposure on progression from HIV seroconversion to immunosuppression, AIDS and death with AIDS. We considered the confound ing effect of study-design related factors (e.g. setting of follow-up), and accounted for pre-AIDS death from natural causes by imputing when each end point would have occurred, had they not died without AIDS. Results Estimates of progression to AIDS and death with AIDS were substanti ally faster after taking pre-AIDS mortality into account. Median incubation time from seroconversion to the first CD4 count <200 cells/mu l was 7.7 ye ars (95% CI : 7.1-8.3) and to AIDS 10.4 years (95% CI : 9.8-infinity). The 10-year survival was 70.3% (95% CI : 62.8-76.6). The relative hazards (RH) of AIDS for IDU from central and southern Europe compared with IDU from nor thern Europe was 1.9 (95% CI : 1.2-3.0) and 1.2 (95% CI : 0.6-2.3), respect ively, before, and 1.5 (95% CI : 0.7-3.2) and 1.1 (95% CI : 0.6-2.3) after taking differences in study-design related factors into account. Accounting for these factors, the RH of death with AIDS was 0.9 (95% CI : 0.3-2.5) fo r central and 1.2 (95% CI : 0.4-3.4) for southern Europe compared with nort hern Europe. For the first CD4 count <200 cells/mu l these figures were 0.8 (95% CI : 0.5-1.4) and 0.8 (95% CI : 0.5-1.4). Age at seroconversion was t he strongest predictor of disease progression. No statistically significant differences in disease progression were found by gender, foreign nationali ty, drug use and potential repeated HIV exposure. Conclusions We found no evidence for regional variability in HIV disease pr ogression among European IDU. Future studies evaluating geographical differ ences should consider the confounding effect of study-design related factor s and differential non-AIDS mortality. As age is an important determinant o f disease progression, it should be considered in recommending treatment.